In 3 GPP (the 3rd Generation Partnership Project) LTE-Advanced (Long Term Evolution-Advanced) standardization, the technique of carrier aggregation (CA) brings along heterogeneous characteristics to cells in an evolved Node B (eNB). An eNB may control a number of cells that operate at different carriers, where some cells may have full or partial overlapping coverage areas. When a user equipment (UE) moves into these overlapping coverage areas, the Downlink (DL) and Uplink (UL) data can be transmitted over multiple carriers, by which data rate can be improved greatly.
When a handover from an eNB (source eNB) to a neighboring eNB (target eNB) occurs with respect to the UE, a target cell, i.e. a cell of the neighboring eNB to which the handover is to be directed, need be selected for the handover.
There exist prior art approaches for target cell selection. For example, Soon Gi PARK et al., US Patent Application Publication No. 2011/0149913, discloses determining an optimal frequency band set for downlink and uplink handover based on measurement information collected by a source eNB from a neighboring eNB and a UE. The measurement information is listed as information measured by the user equipment, information measured within the serving base station, and resource information of the neighboring base station.
However, the measurement information is not sufficient for making an optimal target cell selection among multiple neighboring cells in some cases, such as a case where carrier aggregation is employed, a case where interference is not only from the cells of source eNB, and a case where a UE is moving in high speed.